Power transmission



May 19,19 2- F. T. HARRINGTON ETAL POWER TRANSMISSION Original Filed Feb. 23. 1 938 2 Sheets-Sheet 1 l V Fuuus T.' HARRINGTON & B3000 E Esmrl v v ATTORNEY 1' y 1942- F. T. HARRINGTON ETAL Re. 22,099

POWER TRANSMISSION Original Filed Feb. 23, 1938 Sheets-Sheet 2 I NVENTORS ATTORNEY ReissuedMay 19, 1942 UNITEDA' STATES a PATENT OFFICE- POWER TRANSMISSION Ferris 'r. Harrington, Detroit, men, and ltudolf B. Each, Euclid, Ohio, assignors to Vickers Incorporated,

Mic ll-n Detroit, Mich, a corporation of Original No. 2,186,379, dated January 9, 1940, Se-

rial No. 191,894, February 23, 1938.

Application for reissue December 11, 1941, Serial No. 422,554

llCiaims.

This invention relates to power transmissions and more particularly to those of the fluid type wherein a power transmitting fluid, such as oil, and hereinafter referred to as such, is utilized for the transmission oi power-between one or more pumps and one or more fluid motors.

The invention is particularly concerned with a power transmission system adapted for operating a plurality of hydraulic motors in predetermined sequence and may be used, for example, on a hydraulically operated breaching machine. In the art of surface breaching it has become common to provide dual ramhydraulically operated machines in which one ramdescends in a working stroke while the other ram is caused to ascend simultaneously on its return stroke. Machines of this character areirequently provided with work positioning means which operate to advance and withdraw work holding fixtures to and from working P s tion opposite each breaching tool in proper sequence.

It is an object of the present invention to provide a hydraulic power 11 system adapted to operate a machine of this character automatically in cycles of predetermined sequence which repeat themselves continuously until the machine is stoppedat will.

' Another object is to provide a novel method of maintaining the two rams in step by the provision oi improved preflll means for the circuit connecting the return ends of the two main rams.

Further objects and advantages of the prwent invention will be apparent from the following description, reference being bad to the accompanying drawings wherein a preferred form of the present invention is clearly shown.

Figurelisaaticviewoi'ahydra power ton system incorporating a preferred form 01 the present invention.

l'igurezisatopviewotabroachingmachine,

incorporating the on Fig. 1.

theundersideottbeslideslandl. 'lheplnicns A H and II engage a rack 2i which is connected to a piston rod 23 carrying a piston 25 reciprocable in a work shifting cylinder 21.

- Referring to Fig.1 tank lli contains a supply of oil which may be withdrawn through suction conduits l2 and It, by a-pair of pumps l6 and It adapted to be continuously driven by a suitable prime mover, such as an electric motor, not shown.

10 The pump it has a delivery conduit in which a conventional relief ,valve 22 is-inserted for bypassing oil through a conduit to the tank when-' ever a predetermined pressure is exceeded in the conduit 2|. The conduit 20 extends to the pres- 15 sure port of a solenoid operated, spring centered,

open center, four-way valve 26. The. latter has its tank ports connected to tank by a conduit 2! and its cylinder ports connected to the opposite ends of cylinder 2'! by conduits II and".

go The pump II has a' delivery conduit 34 in whic is inserted a conventional relief valve" for byoil to the tank through a conduit 38 whenever a predetermined pressure is exceeded in the conduit 34. The conduit 34 extends to the pressure port of a solenoid operated, spring centered,

open center, four-way valve 40, having its tanks port. connected to tank by a conduit 42. The

cylinder ports of the valve ll are connected to the head ends 01' the cylinders 2 and I by conduits ll and ti respectively.

The rod ends of the cylinders '2 and I are connected together in a secondary circuit by conduits II and I] which also communicate with a conduit 52 which extends to one cylinder port of 85 spring centered, closed center, tour-way valve it. -The pressure port of the valve 54 is connected to the discharge conduit ll of pump II by a conduit It while the tank ports are connected totank by a conduit 58. The other cylinder port of valve SI is plugged. .From the'discharge conduit 34, a branch conduit 60 extends through a check valve 82 to a hydrostatic flow control valve II which is operable to maintain a constant but adjustable rate of flow therethrough in a mannerweil known in the art. -Prom the valve", a conduit 66 extends to a relief valve II adapted toby-pass oil to the tank through a conduit til whenever a predetermined pressure is exceeded in the conduit 00., From the relief valve 88 the conduit ll extends to the conduit I2 ot-the secondary system.

l'brthepurposeotcontrollingthesolenoid aim at and to, electrical circuit is provided as follow mm startingiswitch pi. normally open, connects one side of a suitable power line LI by conductor 01 to the operating coil of a holding relay 60 and to the other side of the line L2. 'Theholding circuit of relay extends by conductor 12 to a normally closed single circuit relay I4, and conductor to an emergency stop switch 10 to line LI. The relay 00, controls a circuit extending from line LI by conductor 00 to branch conductors 02 and 04. Conductor 02 leads to a double circuit limit switch 00, which is actuated by cam 00 on cylinder 2 whenever it reaches its upward limit-of movement. A conductor 92 extends from switch 00 to adouble circuit limit switch 04 adapted to close circuit 92,

by a cam 06 on cylinder travel. From switch 04 to a normally closed push button stop switch 0 at its lower limit of I00, and thence by aconductor I02 to the upper solenoid of a iour-way valve and to line L2; Branch conductor 04 leads to a single circuit limit switch I04 adapted to be closed by a cam 105 on rodof piston whenever the latter is in its lowermost position. A conductor I00 connects to a conductor .I I0 whichleads to a double circuit limit switch "2 adapted to beopened by cam 96 oncylinder 0 in its uppermost position. A conductor II4 extends from switch II2 to the right hand solenoid of four-way valve .40 and thence to line L2. A'conductor IIO leads off of conductor H4 and extends to limit switch IIO which is adapted to be opened by cam 00 on cylin- .der 2 at its lowest limit of travel. From there a conductor I20 extends tov conductors I00 and H0 completing the circuit. A conductor I2I extendsfrom conductor 04 to'a limit switch I22 which is adapted to be closed by cam I00 on the rod of 'der 21 and holding the piston 25 in its lowermost position as long as the cams 00 and 90 engage the limit switches 00 and 94. is also established to the right hand solenoid of valve 40 through the relay, 00, conductor 00, conductor 04, switch I04, conductor I00, conductor H0, switch II2 and conductor 4. Valve 40 is accordingly shifted to the right to connect the pressure port with conduit 44.

Pressure oil from pump I0 is'delivered through conduit 04, valve 40 and conduit 44 to the head a conductor 00 extends piston 25 when the latter is at its upper-limit of travel. "Aconductor ,I24 extends to limit switch 00, which when closed by lowering of cylinder 2, connects by a conductor I20 to left hand solenoid of four-way valve and thence to line L2. conductor I20 extends from conductor I20 to limit switch 94, which will close when cylinder 0 rises. A conductor I00 connectslimit switch 04 to conductor I24.

Fromrelay 0|, conductor 00, conductor 02 also connects to limit switch III, which will be closed when cylinder 2 has descended. 'From limit switch 0, a conductor I02 extends to limit switch 2 which is closed by rising of cylinder 2.. A conductor I34 extends from switch II2 to push button stop switch I00, from which a conductor I30 extends to the lower solenoid'of fourend of cylinder 2, causing the latter to move downwardly on the broaching stroke. Oil discharged from the rod end passes through the conduits 40- and 50 to the rod end of cylinder 0, causing the latter to move upwardly in synchronism with the downward movement of cylinder 2. As the cylinder -2 reaches the bottom of its stroke and cylinder 3 reaches the top of its stroke, limit switches II! and H2 are depressed thus establishing a circuit to the lower solenoid of valve 20. This circuit is through relay 5!,

conductor 00, conductor 02, switch H0, conductor I32, switch II2, conductor I34, switch I00 and conductor 7 downwardly, connecting pressure oil to the conduit 32 and causing the piston 25 to move upwardly, retracting the slide 0 and advancing the slide 0. The shifting of both limit switches H2 and H0 also opened the circuit to the right hand solenoid of valve 40., permitting the latter to spring center and by-pass the pump I0.

As the piston 25 reaches its upward limit, cam I00 depresses limit switch I22 to establish a circuit to the left hand solenoid of valve 40 through relay 60, conductor 00, conductor 04, conductor I2I, switch I22, conductor I24, switch 00, and conductor I20. Valve 40, accordingly, moves to the left to connect pressure conduit 04 to the conduit 40 to admit pressure oil to the head end of cylinder 0. The latter moves downwardly on a broaching stroke and the oil discharged irom the rod end is delivered to the rod end of cylinder 2 through the secondary circuits 40 and 50, causing cylinder 2 to perform a return stroke. At the start of these movements of cylinders 2 and 0, earns 00 and ride off from limit switches III and H2, deenergizing the lower solenoid of valve .26, permitting the latter to spring center and by-pass pump I6.

As the cylinders 2 and 0 complete their movements, limit switches 00 .and 04 are depressed,

way valve 26 and thence to line L2; From con-,

ductor I34, a conductor I00 extends to stop switch I00 whence conductor I40 connects to a conductor I42 and operating coil of relay [4.

' In operation with pumps I0 and I0 running and with the starting switch 00 open the solenoids of valves 40 and 20 are deenergized, permitting the valves to spring center and by-pass discharge of the pumps. Starting with the parts in the position shown in the drawings,v in which the slide 0 is in working position and the cylinder 2 is ready to start a downward working stroke while the slide 9 is retracted for reloading and the cylinder 0 has completed a working stroke, it will be seen that when starting switch 00 is depressed the upper solenoid of valve 20 will be energized through relay 00-, conductor 00, conconduit 20 of the pump I0 to the conduit 00,

admitting ressure oil to the upper end of a rlin 'again establishing a circuit through relay 09,

conductor 00, conductor 02, switch 00, conductor 92, switch 04, conductor 00, switch I00 and conductor I02, to the upper solenoid of valve 20. The latter moves upwardly to admit pressure oflfrom pump 101.0 the conduit 20 and causes piston 20 to move downwardly,retracting slide 0 and advancing slide 0. The shifting of both limit switch 00 and 04 deenergize'sthe left hand solenoid of the valve 40, permitting the latter to spring center and by-pass pump Is. At the completion of this movement, the parts are restored to the position shown in the drawings, except that relay 00 remains energized so that another cycle takes place immediately and the machine continues in operation through the same cycles, repeatedly.

To stop the machine the push button switch I00 may be depressed. This has the eii'ect of' A circuit I20. Valve 26, accordingly, moves the completion'of a working stroke on either side.

If it is necessary to stop the machine immediately as in an emergency the emergency stop switch ll isdepressed thus opening the holding circuit of relay '8 instantly and deenergizing both solenoid valves. The latter spring center and by-pass both pumps l6 and II. The machine is accordingly stopped in whatever position itmay happen to be when the switch II is opened For the purpose of insuring replenishing oi the secondary circuit to make up for leakage, the flow control valve 64 may be adjusted to whatever rate is found sizitable for given operating conditions so that the proper quantity of oil from the conduit flows through the conduit ll,

check .valve 82, fiow control 84 and conduits it and 51 to the secondary system. The relief valve 68 provides for relieving excessive pressure in the secondary system in case the upgoing cylinder gets to the top before the down-going cylinder gets to the bottom.

It will be noted that either solenoid 01 valve ll remains energized until both of two conditions are fulfilled. The down-going cylinder must reach bottom and'the up-going must reach top position to cut 01! the delivery of fluid to the before the solenoid valve ll can be deenergizcd. The circuit to the right hand solenoid has a parallel branch portion from conductor I'll through conductor H6, switch Ill, and conductor In to conductor Ill which keeps the 40 solenoid energized if cylinder 3 gets to the top before cylinder 1 gets to the bottom. Likewise the left hand solenoid circuit has a parallel branch portion from conductor I24 through conductor llll, limit switch 94 and conductor I28 to conductor I28. Thus the pump is never by- "passed until both cylinders have completed their strokes. Accordingly, pressure is available either to continue downward movement of one cylinder or to continue upward movement of the other cylinder through the prefili feed valve 84 whichever may-be required.

The check valve I2 prevents now of oil out of the secondary system to the tank through conduit 7 34 and valve 40 when the latter is in spring cen- 55 tered position. The reset valve 54 may be utilized to manually exhaust oil from the secondary system should the same become'too full as may happen when adjusting the machine for different set-ups. downwardly, the-conduit S! is connected to tank through conduit 50 thus permitting oil to discharge from the secondary system. Likewise, if, it is desired to quickly make in: lost fluid in the secondary system, the valve 54 may be pushed upwardly to connect the secondary system to the pressure conduit 34 through the conduit it.

, While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming withinthe scope of the claims which follow.

What is claimed is as follows: a 1. In a hydraulic power transmission system the combination of a first fluid motor, a second pressed the first time thereafter that the line I By pulling the plunger valve It so fluid motor, pump means for supplying pressure fluid to operate said motors, electrically operable control means for selectively bythe pump means or causing operation of the first motor in either direction, electrically operable control means for selectively by-passing the pump means or causing operation of the second motor in either direction, an electric circuit operably connected to said control means, a manually operable switch for energizing the control means to start operation of the first motor, switchmeans operated by the fluid motors for energizing the control means to cause said motors to operate in a predetermined sequence and manually operable means for deenergizing both said control means to cause the-pump to be by-passed.

2. In ahydraulic power transmission system the combination of a first fluid motor, a second fluid motor, pump means for supplying pressure fluid to operate said motors, electrically operable means for controlling the delivery of fluid to said motors individually, a first pair of limit switches operated by the first motor at opposite ends of its stroke, a'secend pair of limit switches operated by the second motor at opposite ends of its stroke, a manually controlled switch, an elec: tric circuit connecting the control means and the switches and arranged when the manual switch is operated to one position to cause re-' peated operation of said motors through predetermined cycles including a forward stroke of the first motor, a forward stroke of the second motor, a reverse stroke of the first motor and a reverse stroke of the second motor in sequence, and when the manual switch is moved to another motors.

3. In a hydraulic broaching machine of 'the said motors in repeated predetermined cycles;

said means comprising a plurality of limit switches mechanically operated by said motors and connected in said circuit, and a manually operable switch for controlling said circuit independently of the limit switches.

4. In a hydraulic broaching machine of the type having a pair of oppositely movable main 1 slides, a pair of fluid motors for operating the main slides, a pump forsupplying fluid to operate one motor or the other selectively on a working stroke, means for supplying fluid to return each motor while the other is on a working stroke, electrically operated means for controlling the supply of fluid to the motors on their working stroke, an electric circuit connected to said control means, and means including limit switches in said circuit for causing operation of said motors in repeated predetermined cycles and arranged to prevent initiation of a working stroke of a motor before both complete return of the same and completion of the working stroke of the other motor.

5; In a hydraulic broaching machine of the type having a pair of oppositely movable main slides and an oppositely shiitable work handling member, the combination of a pair of main fluid motors for operating the main slides, a second .fluid motor for operating the work handling member, a pump for supplying fluid to the'main motors to operate one motor or the other selective pumps, an electric circuit connected to said electrically operated control valves, and means for causing operation of said motors in repeated predetermined cycles said means comprising a plurality of limit switches mechanically operated by said motors and connected to said circuit, in a manner to prevent operation of the second motor until both motors have completed their respective working and return strokes.

6. In a hydraulic machine of the type having a pair of oppositely movable slides, a pair of piston and cylinder fluid motors for operating the slides, a pump for supplying fluid to operate one motor or the other selectively on a working stroke, means connecting an end of one cylinder to an end of the other cylinder to form a secondary circuit for causing the return of one motor during the working stroke of the other motor, and means for feeding fluid into the secondary circuit continuously at a constant rate to replace leakage. v

I. In a hydraulic machine of the type having a pair of oppositely movable slides, a pair of piston and cylinder fluid motors for operating the slides, a pump for supplying fluid to operate one motor or the other selectively on a working stroke, means connecting an end of one cylinder to an end of the other cylinder to form a sec- 9. In a hydraulic power transmission system the combination of a pump, a pair of oppositely 1 movablep'iston and cylinder fluid motors, means connecting one end of each cylinder with the pump, means connecting the other ends of "the cylinders together in a secondary circuit for causing movement of one cylinder by fluid discharged from the other cylinder and vice versa, control means for selectively directing pressure fluid from the pump to said one end of either cylinder or by-passing the pump, operating means for said control means, a pilot circuit connected to the operating means, and separate circuit controlling means in said pilot circuit positioned for operation by each motor at each end of its stroke,- said pilot circuit being connected to provide interlocking control of said control means where by the bypassing of the pump is preventing until completion of movement of both motors.

10. In a hydraulic power transmission system the combination of a pump, a pair of oppositely movable piston and cylinder fluid motors, means connecting one end of each cylinder with the pump, means connecting the other ends of the cylinders together in a secondary circuit for causing movement of one cylinder by fluid discharged from the other cylinder and vice versa, control means for selectively directing pressure fluid from the pump to said one end of either cylinder 'or bypassing the pump, electric operating means for said control means, a pilot circuit connected to the operating means,'and separate circuit controlling means in said pilot circuit positioned for operation by each motor at each end of its stroke, said pilot circuit being connected to provide interlocking control of said control means whereby the bypassing of the pump is prevented until completion of movement of both motors.

11. In a hydraulic power transmission system the combination of a pump, a pair of oppositely movable piston and cylinder fluid motors, means connecting one end of each cylinder with the pump, means connecting theother ends of the cylinders together in a secondary circuit for causing movement of one cylinder by fluiddischarged from the other cylinder and vice versa, control means including a spring-centered four-way valve for selectively directing pressure fluid from the pump to said one end; of either cylinder or bymotor or the. other selectively on a working stroke, means connecting an end of one cylinder to an end of the other cylinder to form a secondary circuit for causing the return of one motor during the working stroke of the other motor, and means for feeding fluid into the secondary circuit continuously at a constant low rate to replace leakage, and a manually operable valve for at times admitting fluid to the secondary circuit at ahigh rate.

passing the pump, operating means for said control means, a pilot circuit connected to the operating means, and separate circuit controlling means in said pilot circuit positioned for. operation by each motor at each end of its stroke, said pilot circuit. being connected -to provide interlocking control of said control means whereby the bypassing of the pump is prevented until completion of movement of both motors.

FERRIS T. Hl iRIl-ltINGTON.v RUDOLF E. ESCH.- 

